Family Tree DNA, a genealogy DNA testing company, has launched a free online Y-DNA database called Ysearch <www.ysearch.org>. Users can enter their Y-DNA test results and search for potential relatives. A "conversion page" shows how to translate results from other labs into FamilyTreeDNA's format for easier comparisons.

Genealogy DNA testing — which uses different chromosomes from medical DNA tests — can confirm or disprove relationships between people and estimate the number of generations to their common ancestor. Y-DNA tests utilize the Y chromosome (inherited by males), and can match men who are related through paternal lines. (To be part of Ysearch, a woman would enter a male blood relative's test results.)

You can register with Ysearch by submitting Y-DNA test results, contact information (there are several privacy options) and your most-distant known ancestor. Once you have a user ID, enter it to look for genetic matches. Ysearch had 2,900 registered users as of February.